Quantum chemistry calculations of spectral parameters would be compared with experimental spectroscopy (NMR, IR and Mossbauer) on the active site structures of heme proteins, with the aim to probe heme-ligand bond angles and heme ruffling, particularly in the paramagnetic states. The long term goals are (1) to understand specificity in small molecule binding to heme proteins, and (2) to validate quantum chemical methods for computing NMR shifts, other spectroscopic quantities and energetics in metallo-proteins. Studies of heme proteins and model systems are proposed, including DFT calculations of paramagnetic shifts and Mossbauer splittings. A variety of NMR measurements will be used to refine the structures of myoglobin, carbonmonoxy-myglobin, cytochrome c from the ferricytochrome c-cytochrome c peroxidase complex. Finally, with the help of the understandng of spectroscopy heme systems, and with Dr. Oldfield's refined structures of the proteins, the energetics of binding of small molecules to hemes will be studied, which he hypothesizes are dominated by hydrogen bonding interactions in the cavity.